The asymmetric domino oxa‐Michael–Henry reaction of salicylaldehyde derivatives with trans‐β‐nitro olefins catalyzed by a readily available trans‐4‐hydroxy‐L‐prolinamide with 4‐nitrophenol as an effective cocatalyst is presented. The corresponding 3‐nitro‐2H‐chromenes were obtained in moderate to excellent yields (up to 99 %) and with up to 90 % ee under mild conditions. In addition, a preliminary study shows that this organocatalytic system is able to promote the domino aza‐Michael–Henry reaction of 2‐formylpyrrole derivatives with trans‐β‐nitro olefins to give chiral 2‐nitro‐3H‐pyrrolizines.
Isomers of 9,10-bis(butoxystyryl)anthracene (DSA4), including n-butyl, i-butyl and t-butyl at ortho or para positions, were designed and synthesized. All of them display an aggregation-induced emission phenomenon. Remarkably, it was found that isomerization of butyl endgroups presents significant influences on their piezofluorochromic properties. Thus, an alternative approach to design and obtain piezofluorochromic compounds is proposed here.
Two structurally simple and red light-emitting AIE luminogens, (1,3-dimethyl)barbituric acid-functionalized anthracenes (B-A and DMB-A), were designed and synthesized.
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